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Immune Responses to Invasive GBS Infections

Emerg Infect Dis; 2016 Nov; Edwards, Rench, et al

Increased antibodies to capsular polysaccharide (CPS) and pilus island (PI) during recovery suggests that group B Streptococcus (GBS) bacteremia in adults is potentially vaccine preventable, a recent study showed. Prospective surveillance from 7 hospitals in Houston, TX, identified 102 nonpregnant adults (59% male; 44% white, 30% black, 25% Hispanic) with GBS bacteremia. All patients had ≥1 condition that enhanced risk for invasive GBS disease. Researchers found:

  • 43% had skin/soft tissue infection, 16% bacteremia without focus, and 12% osteomyelitis.
  • CPS types were Ia (24.5%), Ib (12.7%), II (9.8%), III (16.7%), IV (13.7%), and V (12.7%); 9.8% were nontypeable by serologic methods.
  • Pili (89%) were most often PI-2a.
  • CPS and pilus-specific IgG increased during convalescence among patients with strains expressing CPS or PI.
  • All GBS expressed CPS or PI; 79% expressed both.


Edwards MS, Rench MA, Rinaudo CD, et al. Immune responses to invasive group B Streptococcal disease in adults. Emerg Infect Dis. 2016;22(11). doi:10.3201/eid2211.160914.